1. Field of the Invention
This invention relates to machine tools and more particularly to a worktable assembly for machine tools.
2. Prior Art
Machine tools, and particularly tools such as turret punch presses are normally provided with a workpiece supporting table. In the case of turret punch presses, the table has an innermost portion which partially surrounds the lower turret and a forward portion extending a substantial distance in front of the turret. The forward portion has lateral side portions which extend horizontally of the center line of the turrets a considerable distance. A workpiece, such as a sheet of metal, which is to be acted upon by the tools carried in the turrets is then positioned on the worktable and is moved on the worktable into the desired position with respect to the tools carried in the turret.
In order to facilitate movement of the workpiece on the table, the table is normally equipped with anti-friction means, such as rollers or balls. Workpiece gripper carriages are often provided in association with such worktables and include workpiece edge gripper members which are movable in both the X and Y axis with the Y axis lying on a line extending from the center of the turret through the center of the punch station.
Memory controls such as punch tape readers or computers are used to control movement of the workpiece grippers and the gripper carriage so as to accurately position any desired portion of the workpiece with respect to the punch station.
Thus machining of the workpiece is substantially fully automatic from the time the workpiece is placed into the proper position with respect to the grippers to the time machining is completed and the workpiece has been moved free of the turrets.
Thereafter, it is necessary for the machine operator to lift the machined workpiece off of the support table and to place it elsewhere, normally in a storage cart. Additionally, of course, it is necessary for the machine operator to initially lift the unmachined workpiece onto the support table.
Since such machine tools are normally capable of working on quarter inch and thicker workpieces which may have an overall dimension of greater than 3 feet by 4 feet, the workpieces are quite heavy and may be both difficult and dangerous for the operator to move.
It would therefore be an advance in the art to provide method and mechanism for assisting in the removal and/or loading of workpieces on support tables for machine tools.